Blood is the medium which carries everything needed by ever every cell in the body. The shelf life of most blood fractions is measured within a span of only a few days. Therefore, it is highly desirable to find methods by which the shelf life and quality of whole blood and of blood fractions especially of platelets, leukocytes and red cells can be extended.
As used herein, reference to "quality" of whole blood or blood fractions treated in accordance with the present invention means that at the limits of the normal shelf life of like but untreated blood or fraction, the treated blood or fraction better retains the inherent components of the individual cells for a layer time to support normal and necessary physiological functions.
The various component fractions of the blood tissue are of cellular and fluid (plasma) types. Plasma comprises about 60% by vol. of whole blood and the cells comprise about 40% vol. The cellular components include erythrocytes (red blood cells), platelets, and leukocytes (white blood cells). Leukocytes comprise granulocytes (about 55% vol.), lymphocytes (about 40% vol.) and monocytes (about 5% vol.). Granulocytes have the shortest shelf life. The shelf life of lymphocytes and monocytes is somewhat better. The fluid components of blood include those carbohydrates, lipids, salt, minerals, and proteins which contain albumins, globulins, antibodies, and enzymes. The differing fractions can be used for various purposes and, therefore, the same unit of whole blood can yield components which can each find separate applications.
Whole blood is most often fractionated, because its fractions have different shelf lives and one or more fractions in whole blood which lose their viability may contaminate the rest. Furthermore, red cells will retain their shelf life for relatively long periods in the frozen state. Other blood fractions cannot tolerate freezing. The improvement of shelf life is most important for platelets and to a lesser extent for leukocytes. Platelets are in great demand, and extending their shelf life is of great importance. The platelet fraction, or platelets are given to patients in hemorrhagic disorders. Their principal function is to patch small defects in the endothelial lining of blood vessels and to limit hemorrhage by promoting local coagulation of the blood. Currently platelets have an in vitro shelf life of about five days.
Lymphocytes are comprised of two major subclasses, T-lymphocytes and B-lymphocytes. Their primary function is to regulate the immune system to produce antibodies. The antibodies can be effective against bacteria, viruses, or particulate matter. AIDS and AIDS related syndromes are a direct result of improper functioning of T & B cell systems. Therefore, any product which has a positive effect on regulating their shelf life to preserve them for longer periods of usefulness will have a beneficial effect also upon combating AIDS.
White blood cells, particularly T-cells are also used in the biotechnology industry to produce monoclonal antibodies. Such antibodies have an ever increasing application in therapy and have achieved some advances as diagnostic agents, such as in viral or bacterial diagnostic kits and to enhance the development and yield of the antiviral agents.
Platelets generally become unstable after about five days, and even during this period they have to be agitated or gently rotated to keep them from clumping. The number of blood donors has been declining primarily due to the AIDS scare and there appears to be a constant shortage in the available amount of platelets. For example, between 1984 and 1985 the total number of plateletpheresis procedures increased by over 24%. During the same period the total number of blood transfers increased only by merely 3%. This indicates that platelet requirements are significantly increased over the total number of transfusions and this suggests an increase in the proportion of clinical usage of platelets. An increase in shelf life of about two days of the platelets would increase the supply by about 40%. Such an extended supply would mean that the increased present need for platelets would be achieved by fewer blood donors. Hence, the most important need is for the extension of the shelf life of the platelets.